Analyzing Artificial Cervical Disc Replacement

Your dear friend has had pain in her left hip for the past decade, and it has only gotten worse. Her films show severe osteoarthritis, even though she had joint resurfacing just a few years ago. This vibrant, 50-something woman now has so much pain that she can barely get through her day. Her nights are plagued with a dull, persistent ache—she can’t remember the last time she had good night’s sleep.

Your dear friend knows you are a physician, a surgeon. She turns to you for help. You look into her desperate, hopeful eyes and suggest…hip fusion surgery? Of course, not. So why do so many surgeons routinely recommend anterior cervical discectomy and fusion (ACDF) for cervical disc disease?

A good surgery, until there were others options

Hip arthrodesis had a very successful history, in the 20th century. For people with hip arthritides, hip fusion surgery relieved pain and provided a strong, stable hip. When total hip replacement surgery became available, however, hip fusion surgery fell out of favor. Why? One could say it was because hip fusion surgery was limited by low back pain, ipsilateral knee pain, and degenerative arthritis in the contralateral hip. One could also argue it is difficult to convince patients who know about the many benefits of hip replacement to opt for fusion. While hip arthrodesis remains a viable option in select patients, it is far from the best choice in a world with total hip arthroplasty.

The case for arthroplasty (in the cervical spine)

In our analogy, spinal fusion may be thought of as the hip arthrodesis of the spine; it creates a strong, stable joint, but range of motion can be limited. Like hip arthrodesis, spinal fusion places abnormal stresses on adjacent joints, which may accelerate degeneration.

Artificial cervical disc replacement, on the other hand, is the total hip arthroplasty of our spine surgery saga. Nearly 20 clinical trials now show cervical disc replacement results in better functional outcomes, fewer adverse events, and fewer surgical revisions and reoperations than ACDF. This reflects what I have seen in my own spine surgery practice: patients who opted for cervical disc replacement tend to recover from surgery more quickly, have substantially better range of motion, and better long-term outcomes than my ACDF patients.

A not-so-uncommon patient story

A significant minority of patients I see in my practice is exemplified by Joe, a man I treated with artificial cervical disc replacement. Joe (not his real name) came to me with persistent neck pain. His pain persisted even after another surgeon had performed an ACDF. His CT showed very little bone growth. Also, there were halos around the screws, which means the screws are loose. Simply put, the man’s spine hadn’t fused properly, he had a non-healed fusion.

A non-healed fusion isn’t all that common—fusions have a 93% success rate overall—but what was common was the story he told me about his experience with the first surgeon. I asked him if he had been offered cervical disc replacement. Joe replied, “I was told I wasn’t a candidate for cervical disc replacement.” Joe was actually the perfect candidate for cervical disc replacement surgery: young, active, and otherwise healthy. In most circumstances, anyone who is a candidate for ACDF is also a candidate for replacement.

So if your dear friend came to you with debilitating cervical disc disease, would you suggest fusion? What is more, would dissuade her from replacement? Why are spine surgeons routinely doing this very thing?

Yet cervical spinal fusion reigns

I can only postulate why spine surgeons are guiding patients to fusion over replacement for cervical disease. By my estimation, the most glaring reason is the technical rigor required to replace a cervical disc. The device must be precisely orientated in three planes, with only a couple of millimeters of tolerance in any direction. In other words, it is a technically challenging surgery.

It is likely also true that most spine surgeons were largely trained on anterior and posterior fusions, not replacements. Given the technical rigor of the procedure, it is quite possible that many surgeons to not feel sufficiently qualified to perform cervical disc replacement. There is little incentive to seek additional training, either. The reimbursement for ACDF is substantially larger than it is for cervical disc replacement. So surgeons must undergo additional training to learn how to perform a more complicated procedure for less money.

Cervical disc replacement should be offered

Not all patients will benefit from cervical disc replacement, but at least they should be given the chance to decide for themselves. An elderly patient with limited mobility who is comfortable in an easy chair will probably love his spinal fusion, but a 50-year-old golfer shouldn’t be forced down the fusion pathway. We can give our active patients, active spines, but only if they know the option is available to them.

If you want to become more proficient in cervical replacement, additional training is available. If you don’t want to offer cervical replacement, think of your dear friend and refer her to someone that can provide that option.

Schafroth MU, Blokzijl RJ, Haverkamp D, et al. The long-term fate of the hip arthrodesis: does it remain a valid procedure for selected cases in the 21st century? International Orthopaedics. 2010;34(6):805-810.